The delivery of biologically-active agents through a biological surface is a well-recognized method of treatment in controlled drug delivery. Such compounds are often delivered from a device to a skin surface, with transdermal delivery through the skin.
The treatment of the skin of humans and animals with topical drugs, antibiotics, antimicrobial agents, anti-infective agents, and pain-relieving agents is well known. In recent years transdermal delivery of biologically active substances has gained favor because of the controlled release of a minimalized concentration of the active agent. The initial systems for transdermal delivery pertained to patches containing small, lipophilic drugs, such as scopolamine, nicotine, estradiol, fentanyl, lidocaine and testosterone, as well as combination patches containing drugs for contraception and hormone replacement. Following the initial patch studies, transdermal chemical enhancers were studied, as well as non-cavitational ultrasound and iontophoresis. More recent developments for penetrating the stratum corneum of the skin involve microneedles, thermal ablation, microdermabrasion, electroporation, and cavitational ultrasound. Since the inception of transdermal drug delivery patches, it is believed that more than one billion transdermal patches are manufactured each year. However, it has been difficult to exploit the transdermal route to deliver hydrophilic drugs (M. R. Prausnitz and R. Langer, Nat. Biotechnol., November, 26(11), 1261-1268 (2008)).
A commercially successful application for the use of a non-stinging, volatile, hydrophobic solvent on human and veterinary skin has been in the area of liquid adhesive bandages. These bandages are prepared from siloxy-containing hydrophobic and amphiphilic polymers admixed with volatile liquid polydimethylsiloxanes and volatile liquid alkanes (U.S. Pat. Nos. 4,987,893, 5,103,812, 6,383,502, and 8,263,720, the entireties of which are incorporated herein by reference). They have been reported to provide non-stinging, non-irritating liquid bandage coating materials after solvent evaporation that allow body fluid evaporation while protecting the body surface from further contamination and desiccation. Over time, these polymer coatings self-remove from the skin as healing occurs. Certain hydrophobic drugs, such as isopropyl xanthic disulfide, a fungicide, can dissolve directly in these hydrophobic, volatile solvents (U.S. Pat. No. 5,103,812) without the use of any additives. However, hydrophilic (e.g., polar or ionic) biologically-active agents, such as pharmaceutical drugs, antimicrobial agents, anti-infective agents, and pain-relieving agents are not soluble in the hydrophobic volatile solvents.